Recently, reduction of processing effluent is required for environmental protection. Hydroquinones which have been conventionally employed as a developing agent are unacceptable in terms of safety so that ascorbic acids and their derivatives (e.g. reductones) were studied as substitutes for the hydroquinones. However, the ascorbic acids have the disadvantage of lowering the pH of a developer due to aerial oxidation, resulting in retarding development reaction and lowering development activity. Therefore, it causes the problem in that it is technically difficult to maintain the pH at low replenishing rates.
Developers are generally supplied in the form of a concentrated solution or powder, which are diluted with or dissolved in water to make a developing solution. During the storage, the concentrated solution or solid processing chemicals are subject to oxidation by oxygen in ambient air. The oxidation causes lowering of the concentration of the developing agent or preservatives, or lowering the p H, resulting in deterioration of developability after storage. Thus, the concentrated solution or solid processing chemicals are subject to deterioration during long-term storage so that a technique whereby no deterioration in developability occurs even when kept over a long term, is desired. Further, there is desired development a developer exhibiting stable photographic performance without variation in processing, even when subjected to continuous processing over a long term.
U.S. Pat. No. 1,420,656 and JP-A 54-3532 (herein, the term "JP-A" refers to unexamined and published Japanese Patent Application), for example, disclose a technique which prevents oxidation of the developing solution, in which an amine compound is incorporated as an antioxidant for a color developing agent. However, there is not disclosed a technique for preventing pH- lowering due to oxidation of a developing solution containing ascorbic acid (reductones), as a developing agent, and maintaining development activity. The use of a large amount of the carbonate buffer is known as a technique for maintaining the pH of the developing solution, and an increased addition of a sulfite or addition of a preservative is known as a technique for maintaining the activity. These techniques, however, are insufficient to maintain the pH, and are not preferable since the salt concentration of the developing solution is increased, lowering developability.